Gas turbines range in size from micro-turbines at less than 50 hp (37.3 kW) to large industrial turbines of greater than 250,000 hp (190 kW). The noise produced by gas turbines is primarily high-frequency noise which is generated in the air inlet of the turbine, with a smaller amount coming from the turbine exhaust. The main components of the intake noise generated from the gas turbine are the frequencies generated by the rotation of the turbine's compressor.
Typically, the noise produced in the turbine air inlet is attenuated using an inlet silencer, which is installed in the air inlet ducting between the air filter and the turbine air compressor inlet. A conventional intake silencer used in a large gas turbine typically includes a noise reduction structure comprised of a plurality of sound-absorbing splitters disposed in parallel along a gas flow direction. Typically, the noise reduction efficiency of a conventional intake silencer is not ideal because of a mismatch in noise frequencies to be reduced and the frequencies that can be reduced by the conventional intake silencer. Often, the length the intake silencer is increased based on the amount of noise reduction to be achieved, and thus, typically, the intake silencer is heavy because the splitters are made of a steel frame covered by steel perforated plates that contain sound absorption materials, such as mineral wools.
Thus, a problem that is solved by the present invention is a reduction in the length and a decrease in the cost of the heavy duty gas turbine inlet side due to the combining of two stages of inlet silencers and the turbine inlet bleed heat system.